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These courseware materials are to be used in conjunction with Software Engineering: A Practitioners Approach,5/e and areprovided with permission by R.S. Pressman & Associates, Inc., copyright 1996, 2001

Chapter 24Technical Metrics for

Object-Oriented Systems

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These courseware materials are to be used in conjunction with Software Engineering: A Practitioners Approach,5/e and areprovided with permission by R.S. Pressman & Associates, Inc., copyright 1996, 2001

Distinguishing Characteristics

Localizationthe way in which information is concentratedin a program

Encapsulationthe packaging of data and processing

Information hidingthe way in which information about

operational details is hidden by a secure interface Inheritancethe manner in which the responsibilities of one

class are propagated to another

Abstractionthe mechanism that allows a design to focus onessential details

Berard [BER95] argues that the following characteristics require

that special OO metrics be developed:

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These courseware materials are to be used in conjunction with Software Engineering: A Practitioners Approach,5/e and areprovided with permission by R.S. Pressman & Associates, Inc., copyright 1996, 2001

Class-Oriented Metrics

weighted methods per class

depth of the inheritance tree

number of children

coupling between objectclasses

response for a class

lack of cohesion in methods

Proposed by Chidamber and Kemerer:

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These courseware materials are to be used in conjunction with Software Engineering: A Practitioners Approach,5/e and areprovided with permission by R.S. Pressman & Associates, Inc., copyright 1996, 2001

Class-Oriented Metrics

class size

number of operations overridden by asubclass

number of operations added by a subclassspecialization index

Proposed by Lorenz and Kidd [LOR94]:

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These courseware materials are to be used in conjunction with Software Engineering: A Practitioners Approach,5/e and areprovided with permission by R.S. Pressman & Associates, Inc., copyright 1996, 2001

Class-Oriented Metrics

Method inheritance factor

Coupling factor

Polymorphism factor

The MOOD Metrics Suite

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Operation-Oriented Metrics

average operation size

operation complexity

average number of parameters per operation

Proposed by Lorenz and Kidd [LOR94]:

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These courseware materials are to be used in conjunction with Software Engineering: A Practitioners Approach,5/e and areprovided with permission by R.S. Pressman & Associates, Inc., copyright 1996, 2001

Testability Metrics

encapsulation related lack of cohesion in methods

percent public and protected

public access to data members

inheritance relatednumber of root classes

fan in

number of children and depth of inheritancetree

Proposed by Binder [BIN94]:

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These courseware materials are to be used in conjunction with Software Engineering: A Practitioners Approach,5/e and areprovided with permission by R.S. Pressman & Associates, Inc., copyright 1996, 2001

OO Project Metrics

number of scenario scripts

number of key classes

number of subsystems

Proposed by Lorenz and Kidd [LOR94]: